1. Field of the Invention
This invention relates generally to passenger vehicle occupant restraint systems having air bag modules and, more particularly, to a system for venting an air bag module.
2. Background Art
Occupant restraint systems employing air bag modules are well known. During a collision of a predetermined magnitude, an air bag cushion is inflated by an inflator and is deployed in the vehicle for protection of the vehicle occupant. The air bag cushion is deployed at a relatively high rate of speed and force optimized to protect a wide range of occupants under various conditions. There are, however, times when a reduced amount of air bag cushion pressure and force is desired, e.g., when an occupant is out of position during the vehicle impact, during a less severe accident, when the occupant is properly belted, or when the occupant is of a smaller stature. Various vehicle occupant restraint systems having air bag modules have been designed to vent gas from the air bag cushion, thereby reducing the force of the air bag deployment. One technique uses vents on the air bag cushion which are always open. In other systems, vents in the air bag cushion are opened when the pressure inside the air bag cushion reaches a predetermined level. However, these systems are dependent on external forces, such as an out of place occupant, causing the pressure inside the air bag cushion to reach a predetermined level and do not take into account any other crash factors.
In another system disclosed in U.S. Pat. No. 5,234,229, issued to Gordon, an air bag inflator is connected to a base plate using retainer posts to allow fore-and-aft movement of the air bag inflator. Springs bias the inflator through an opening in the base plate and create a seal. An air bag cushion is attached to the base plate around the periphery of the opening, thereby creating a sealed or closed system encompassing the inflator. During a collision, the inflator inflates the air bag cushion. When a predetermined amount of external force is applied to the air bag cushion such that it compresses the springs, the inflator is pushed back away from the base plate breaking the seal and gas is vented. This decreases the pressure in the air bag cushion. This system is also dependent only on the amount of force exerted on the air bag cushion and does not take into account other crash factors.
It would be desirable to provide a variable venting occupant restraining system comprising an air bag module which is selectively activated based on the occupant and the crash conditions.
It is an object of this invention to provide a variable venting occupant restraining system comprising an air bag module wherein the deployment of the air bag cushion is dependent on the occupant and other crash conditions.
Accordingly, this invention features a system for venting an air bag module comprising an air bag cushion retainer ring, an air bag cushion secured to the air bag cushion retainer ring, an inflator for generating gas to inflate the air bag cushion, at least one spring positioned and compressed between the inflator and the air bag cushion retainer ring such that the spring biases the inflator away from the air bag cushion retainer ring, a quick-release device securing the air bag cushion retainer ring to the inflator and maintaining the spring in a compressed position, sensors to sense occupant and crash information, and a restraint control module electrically connected to the quick-release device and for receiving information from the sensors and computing if venting is required. If variable venting is required, the restraint control module signals the quick-release device to release the air bag cushion retainer ring from the inflator and to allow the spring to urge one of the inflator or air bag cushion retainer ring away from the other of the inflator or air bag cushion retainer ring to create an opening between the retainer ring and the inflator to allow venting of the gas from inside the air bag cushion.
In one embodiment, the inflator is urged away from the air bag cushion retainer ring. In a second embodiment, the air bag cushion retainer ring is urged away from the inflator.
The quick-release device may be pyrotechnic rivets or other quick release methods.
These and other objects of this invention will be more readily apparent upon reference to the following detailed description.